Test tube rack



FIG. 1 is a plan view of an unassembled test tube rack shown flat, showing my new design;

FIG. 2 is a perspective view of the tube rack shown in condition of use at the first step of assembly;

FIG. 3 is a perspective view of the tube rack shown in condition of use at the second step of assembly;

FIG. 4 is a perspective view of the tube rack shown in condition of use with the test tube rack shown fully assembled; and,

FIG. 5 is an enlarged view of a portion of FIG. 1 showing portions of the lettering and numbering in greater detail. 

The ornamental design for a test tube rack, as shown and described. 